Temperature regulator



y 1937. H. o. ROOSENSTEIN 2,088,217

TEMPERATURE REGULATOR File d Feb. 5, 1954 INVENTOR HANS OTTO ROOSENSTEINATTORNEY Patented July 27, 1937 UNITED STATES PATENT er -riceTEMPERATURE REGULATOR poration of Germany Application February 5, 1934,Serial No. 709,680

In Germany January 6, 1933 2 Claims.

This invention relates to an improved thermostat for the stabilizationof temperatures in high frequency apparatus.

Most of the frequency-governing elements in 5 high-frequency apparatushave the property that they are dependent upon the ambient temperature.In order that disturbances due thereto may be avoided it is customary toenclose them in thermostats which serve to stabilize the temlO peratureto the requisite degree. In most instances simplearrangements wil.sufiice to this end, and in these what is known as a bimetal strip isemployed to act as the temperature-responsive element, the said bimetalstrip by way of suitable i5 relay means cutting the heating current ofthe thermostat in and out in dependence upon the temperature thereof..The danger and risk of sticking of the contact surfaces makes itnecessary in this connection to choose the current 20 to be broken bythe bimetal strip as low as possible. To this end the said bimetal stripis inserted, for instance, in the grid circuit of a triode tube in sucha way that when the contact is closed the grid is fed by way of thecontact surfaces with 5- a negative biasing voltage which causes adecrease in the plate current. Now, this change of the plate current isutilized for the purpose of disconnecting and reconnecting the heatingcurrent of the thermostat by the aid of suitable re- 30 lay means.

In the practical operation of arrangements of this kind it has beendiscovered that in the course of time changes occur in the regulatingtemperature. A closer examination of this condition showed that thetrouble is ascribable to feeble high-frequency currents which willoccasion at the contact surfaces effects of the sort-usefully employedformerly in coherers. In order to overcome this difficulty very carefulchoking of the 40 bimetal strip is necessary, though this means anundesirable complication in the arrangement.

This inventionwill best be understood by referring to'the accompanyingdrawing, in which:

Fig. 1 shows an improved thermostat of this 45 invention and a heatercircuit connected thereto;

Fig. 2 is another modification of a. thermostat element of thisinvention; and

Fig. 3 is still another embodiment of this invention, employing anexternal magnet for ac- 50 tuating the contacts of the thermostat.

Now, according to this invention the undesirable effect of radiofrequency currents as stated may be considerably diminished by anarrangement whereby the contacts interrupting the our- 55 rent areenclosed in a thoroughly rarefied space or chamber.

Fig. 1 shows an exemplified embodiment wherein the basic idea of theinvention is realized. The negative grid voltage of the triode tube I isconnected and disconnected by the vacuum switch 2 by the aid of anoperating rod 3 drawn through an elastic glass tube actuated by thebimetal strip 4 as known in the art. Included in the plate circuit ofthe tube is the relay 5 which serves. to connect and disconnect theheating current flowing through the heater l winding 6. This arrangementallows of the use of vacuum switches of extremely smaller dimensions,and in this manner an excellent temperature constancy and stability isobtained. When larger switches are employed, then simpler cirlcuit-schemes may be resorted to because of the higher current-carryingcapacity, the vacuum switch being then used, for instance, to directlyswitch the exciting current of the main relay 5 without the intermediaryof the tube I.

A particularly simple circuit scheme is realized if in lieu of thecombination comprising the bimetal strip and separate vacuum switch thebimetal strip itself is provided with contact surfaces, and by disposingthe device inside a vacuous space. In order that the adjustability ofthe temperature and of the contact lost in this arrangement may berestored, recourse may be had, for example, to a setting lever l or 8(Fig. 2) actuuated in the vacuum by an elastic glass tube or 3 the like,or else by magnetic actuation of the contact motion effected from theoutside as shown in Fig. 3 by magnet Mg and iron piece Fe, which issupported above the chamber and energized by a winding W.

I claim:

1. A temperature controlled switch comprising a chamber in the form ofan elastic glass tube having rarefied atmosphere, each end of saidchamber having a depending portion extend- 4o ing within the chamber,said chamber having a bi-metallic strip located within said chamber andsupported by one of said depending portions, a pair of contacts withinsaid chamber, one of said contacts located on and actuated by saidbi-metallic strip, the other contact being supported by a member passingthrough the other depending portion of said chamber, an iron membersecured on said bi-metallic strip, a magnet having a winding locatedoutside of said chamher and arranged to actuate said switch contactswhen current is passed through said windings.

2. A temperature controlled switch comprising a chamber in the form ofan 'elastic glass tube having rarefied atmosphere, each end of said by amember passing through the other depending portion of said chamber, aniron member secured on said bi-metallic strip, an eiectro-magnetcentrally located outside oi. said chamber and arranged to pass currentthrough the windings -5 of said electro-magnet.

HANS O'I'IO ROOSENSTEIN.

